Effect of fretting in aluminium-to-tin connections

The degradation of aluminum-to-tin plated electrical connections under fretting conditions has been studied. In addition to contact resistance measurements, scanning electron microscopy (SEM) and X-ray fluorescence (EDX) analysis were used to study the processes involved. It was shown that fretting adversely affects the contact resistance of aluminum-to-tin plated connections, which show a rapid increase and substantial fluctuations after prolonged exposure to fretting. Two sustained plateaus in the contact resistance characteristics were observed: one coinciding with the melting voltage of tin and aluminum, and the other in the range corresponding to the voltage range of the melting, sublimation, and decomposition of the oxides and vaporization of contact materials. The effects of fretting were reduced significantly by applying higher contact loads. SEM and EDX analyses revealed that considerable damage of the contact zones resulted from the fretting action and substantial exchange of material occurred.